The present invention relates generally to the making of molded bodies from ligno-cellulose particles, and more particularly to an apparatus for making such bodies.
Molded bodies made from ligno-cellulose particles are already known. Such particles may be in the form of chips and fibers and have suitable binder material or materials added to them, whereupon they are subjected to compression in a suitable die or mold to receive the configuration desired. It is conventional to provide one mold having a cavity and another mold or die which can enter into this cavity and which presses between itself and the surfaces bounding the cavity the mixture of particles and binder to the desired configuration.
The problems with this known molding of such particles exist if the finished body is for instance to have two surfaces which include a steep angle with one another, such as surfaces on obliquely inclined side walls of hollow bodies including trough-shaped containers or the like, of flanges or arms on bodies of profiled cross-section, of plate- or strip-shaped parts of molded bodies, and the like. In circumstances where the angle between the adjacent surfaces and the direction in which molding pressure is applied is sufficiently large, no difficulties exist because the mixture of ligno-cellulose particles and binder is simply made to the required thickness in accordance with the desired compression ratio, and then introduced into the mold cavity in suitable manner, for instance manually or by means of a mechanical device. Thereupon, the molding operation is carried out.
Problems arise if the size of the angle, that is the dispersing angle, included between the inclined surfaces and the direction in which pressure for molding purposes is exerted, is exceeded; then these bodies must be produced in such a manner that the mixture is first introduced into an area which is defined, for example, between the surfaces of a core and the pressure surfaces of lateral dies, with a quantity of the mixture which is intended for forming the horizontal or substantially horizontal surfaces of the body being usually placed upon the upwardly facing surfaces of this core. Now, suitable dies are moved into the mold from above and from one or more sides until the material has been compressed to the desired extent. It is also possible to insert certain portions of the mold or die into the cavity from above and other ones from below, simultaneously or in a predetermined sequence. These approaches are not entirely satisfactory because they are very complicated and expensive, especially because the dies utilized must be accurately constructed to insure proper operation of the molding apparatus. Also, the number of different dies and molding tools is relatively large which increases the cost of an apparatus utilized for such purposes.
Attempts have been made to solve the problem if the body to be molded is to be a hollow body, by molding the body piecemeal. This is done by molding individual portions of the body which can be molded in flat or substantially flat shape, and the thus-obtained blanks which are produced in a cold-molding state, are subsequently jointed in a hot-molding process to combine them and form of them an integral hollow body. However, this is quite clearly very complicated and requires a large number of individual tools so that this approach is expensive. Aside from this it will be appreciated that the application of this approach is limited to hollow bodies whose configuration lends itself to the initial manufacture of flat or substantially flat blanks which can then be subsequently united, and it is clear that there are many configurations of hollow bodies to which this approach is simply not applicable.